In the typical dry cleaning process, a small amount of dry cleaning waste water is formed, generally consisting of a mixture of water and a dry cleaning solvent. The waste water also contains solid particulate matter, such as dirt or lint, which is often suspended in the mixture. Perchloroethylene is the most common dry cleaning solvent in commercial use today.
Traditionally, this waste water mixture was merely disposed of. However, it has become increasingly important that the water and solvent be separated, both for economic and environmental reasons. By reclaiming the solvent from the waste water, the solvent can be re-used in the dry cleaning process, reducing the operational cost of a dry cleaning establishment. Further, environmental considerations require that none of the solvent be permitted to be disposed into the environment.
Systems that reclaim solvent from dry cleaning waste water mixtures are known. For example, U.S. Pat. No. 4,637,232, entitled "Apparatus for the Recycling of Solvent Used in Dry-Cleaning Machines and Similar Equipment," issued to Zucchini, discloses a distillation apparatus which separates the solvent and water components. Zucchini discloses the use of a distillation chamber which vaporizes the azeotropic mixture of solvent and water, and produces a fluid which condenses to pure solvent. This solvent can then be drawn away for use in the dry cleaning process. The remaining waste water mixture is then repeated through the distillation apparatus, along with additional waste water generated by the dry cleaning process.
While Zucchini solves the problem of recycling the solvent, it raises new problems. First of all, the azeotropic mixture is highly corrosive due to the formation of hydrochloric (HCl) acid from the chloride solvent and water. This acidity is especially damaging to metallic components of the apparatus. Zucchini attempts to control this by keeping the mixture predominantly solvent. However, even trace amounts of HCl can damage the distillation chamber and tank. An additional problem is the disposal of the remaining water. Since solvent continues to remain in the mixture with water, the water cannot be safely disposed.
Other systems are known which can also purify the solvent from the waste water mixture, such as U.S. Pat. No. 4,513,590, entitled "Combination Filter Apparatus for Use with a Dry Cleaning Machine," issued to Fine, and U.S. Pat. No. 4,354,364, entitled "Dry-Cleaning System," issued to Holder et al. However, neither of these references provide an apparatus or method to purify the water from the waste water mixture.
Thus, it would be desirable to provide an apparatus which decontaminates the dry cleaning waste water mixture, resulting in both pure solvent and pure water. It would be further desirable to provide a method for decontaminating the dry cleaning waste water mixture, to be used in conjunction with such an apparatus.